Wide area radio communication systems are known to include a plurality of local coverage areas that are linked to provide wide area coverage. Subscriber units, which include mobile radios, such as Spectra mobile, and portable radios such as Saber Portable. As these subscriber units roam throughout the wide coverage area, and eventually from one local coverage area to another, ongoing calls must be handed over from one local system to another. The local coverage area is limited by the subscriber output power level. This limitation is commonly referred to in the art as talk-in range. By contrast, fixed base stations are placed on high towers and typically generate relatively large output power levels, as compared with the subscriber units. This disparity between the so-called talk-out range and talk-in range presents problems to the system designer. That is, the overall system coverage is inherently limited by the subscriber, which results in a substantial under-utilization of the functionality of the base stations.
In time division multiplexed (TDM) based radio frequency (RF) communication systems, there is another limitation to system coverage. As a subscriber moves away from the fixed base station, the so-called round trip delay (i.e., from the subscriber to the station and back again) increases. This increased delay causes the subscriber to migrate (in time) toward another subscriber's allocated time slot. Thus, the width of the time slot can be a significant factor in limiting system coverage in a TDM-based RF communication system.
Accordingly, there exists a need for a wide area TDM radio communication system that is not constrained by the shortcomings of the prior art. In particular, such a system that does not require an undue proliferation of costly and complex base stations throughout the wide coverage area would be an improvement over the prior art. Moreover, a system that accounted for conflicts created among subscribers vying for communication resources throughout the system would be a further improvement over the art.